Process of reducing tungstic oxide to tungsten metal



W. F. BLEECKER.

PROCESS OF REDUCING TUNGSTIC OXIDE T0 TUNGSTEN METAL. APPLICATION FILED JULY 8. I920.

1,427, 1 87, Patented Aug. 29, 1922.

1 NV EN TOR.

A TT ORNE Y.

UNITED STATES PATENT OFFICE.

WARREN r. 'IBLEECKER, .or BOULDER, CoLonAnO, ASSIGNOR TO THE TUNGSTEN rzaonuc'rs COMPANY, or BOULDER, COLORADO, A CORPORATION OF COLORADO.

PROCESS OF REDUCIL TG TUNGSTIC OXIDE TO TUNGSTEbT METAL.

Specification of Letters Patent.

Patented Aug. 29, 1922.

Application filed July 8, 1920. Serial No. 394,630.

' the difliculties encountered in the usual procthe application of heat exteriorly of receptacles in which it is contained.

Inasmuch as the reduction proceeds from the outside inwardly molecule by molecule ess of reducing tungstic oxide by until the entire mass is reduced, the old process is extremely slow, it being apparent that it would be imflpractical to pack the material in layers s11 ciently thin to provide for a more rapid permeation of the heat required for reduction.

In the present process as will hereinafter heat is applied interiorly of a mass of oxides-to be reduced, in the presence of a suitable carbonaceous reducing agent and is compelled to permeate mass by the prothrough which the to a point of uniformly through the vision of voids or ducts gases of reduction may pass escape.

By this method a mass of oxides is heated rapidly and uniformly by a continuous circulation of heat in all directions from an interior point of radiation.

. The tungstic oxid may be obtained by any of the well-known methods at present in use, althoughI prefer to employ the granular product of the process of producing tungstle oxid from sodium tungstate described in my application for patent, Serial No. 387,670 filed June 9, 1920, and allowed May 7, 1921.

In this process the tungst1c oxide is obtained by mixing a moist sodium tungstate with an amount of sulphuric acid, eating the mixture for the formation of tungstic oxide and sodium sulphate, and removing the sulphate and other soluble salts by proper washing. practically insoluble tungstlc oxide 1n granular form, particularly well adapted for use in. producing metallic tungsten by the present process.

The result of this process is a.

In carrying out my process I employ an electrlc furnace of suitable construction of either the conductive heat, reflecting are or res1stance type. i

A furnace speciallyconstructed for use in carrying out the process has been shown in longitudinal section in the accompanying drawings, and in the following description reference will be had thereto by the use of numerical characters of reference.

The furnace shown in the drawings embodies an arcing orheating chamber 2 below -a reduction chamber 3 from which it is separated by a carbon or graphite partition 4 upon which the charge is supported. I

The partition is preferably made of carbon or graphite rods spaced apart to provide passages for the gases developed in the heating chamber, and the reduction chamber is normally closed by a roof 8 which is removed to charge the furnace.

The chambers have linings of a nonconductive materal, that of the heating chamber being preferably composed of electrically fused magnesite and that of the reduction chamber of ground coke or graphite rammed in place.

Two electrodes 5 extending oppositely into the heatipg chamber through water-cooled openings in apart to which the material is heated.

The tungstic oxid to be reduced to metallic tungsten is mixed with a preferably carbonaceous reducing agent either before or after it is placed in the furnace.

The reducing agent may be a solid carbonaceous material such as finely ground coke, coal, charcoal or wood, a reducing gas such as hydrogen, carbon-monoxide. methane, gasoline or kerosene vapors or water gas, or a mixture of both.

"in case a solid reducing agent is used, the

tungstic oxid and the carbonaceous material are thoroughly mixed and the mixture placed in the reducing chamber of the furnace or in using a gaseous reducing agent the tungstic oxid is placed in the reducing chamber without preliminary preparation and the gas is introduced into the charge of the furnace through one or more tubes passing through the wall of the structure in connection with a conveniently placed source of In either case the charge of tungstlc oxid the wall thereof are spacer with or without the reducing agent is packed in the reduction chamber of the furnace either in the form of briquets or by means of suitable ramming forms.

Irrespective of the reducing agent used the spaces of gas voids are made throughout the charge to permit of a continuous circulation of heat and gases of reduction while the process is carried on. The spaces or gas voids may be produced either by the use of metal rods which are removed as soon as the charge is packed in the furnace, by distributing a number of small wooden rods throughout the charge which are consumed as soon as the mass is heated and thus provide voids, or by providing the furnace with a series of tubes made of carbon or some highly refractory fused substance such as silica or alundum which are placed in an upright position throughout the charge in' the reduction chamber in connection with the heating chamber belo wwthe same.

In the first two constructions the heat and gases or reduction passing through the voids will enter the porous mass at any point thereof, whereas in the last-mentioned construction the gases must necessarily rise in the metal tubes and then work downwardly through the mass. i

The tubes in this case function more as conductors of heat'tlran as a means for ap- "plying a gaseous reducing agent.

In the drawing the reference numeral 6 designates the charge of tungsten oxide, 7 the wooden or metal rods or tubes disposed therein, and 10 a tube for the introduction of gas into the charge.

Another method of producing the voids consists in mixin the mass with a combustible material sue as sawdust, shavings or small pieces of wood which during the progress of the process are consumed and thereby increase the porosity of thecharge.

In case the material inthe reduction chamber is loosely packed, the means for the production of artificial voids may be omitted.

After the furnace has been charged by any of the above-described methods, and its 8 is replaced, and luted so as to leave a small vent 9 for the escape of various gases or reductlon, the electric circuit in which the electrodes are connected is closed to produce an arc in the heating chamber-of the 'fur- 4 to the reduction. temperature, the gases acting upon the reduction agent arereduced.

and then acting upon the tungsten oxids reduce them in turn until the entire mass has been converted to metallic form.

From this it will be understood that reduction takes place through the medium of gas or vapors which are present in the furnace rather than by actual contact of particles of tungstic oxide and carbon.

In using a solid reducing agent such as coke the theoretical amount thereof, plus an excess of from. 5 to 10% is mixed with the granular oxides after the coke has been ground to the desired fineness.

thereby causing dust and consequent loss of material. I I

It has been found that during the process sulphur contained in the tungstic oxides is volatilized to such an extent as to render the finished metal sufiiciently low in sulphur to meet the most exacting technical requirements and in order to obtain the maximum elimination of sulphur, care must be taken that as little iron as possible is entered into the material by contact with iron utensils or apparatus, or other causes.

What I claim and desire to secure by Letters Patent is:

1. The herein described method of reduc-- ing tungstic oxides to metallic tungsten consisting in applying heat interiorly of a mass of tungstic oxides in the presence of a suitable reducing agent, said mass having artificially produced voids or passages for the circulation of gases.

2. The h rein-"described method of reducing 'tungstic: oxides to metallic tungsten consisting in terspersing combustible matter in a mass o'f tungstic oxides to produce artifici a1 voids or passages for the circulation of gases, and applying heat interiorly of said mass in the presence of a suitable reducing agent.

3. The herein-described meth'od'ofreducing tungstic oxides to metallic tungsten consisting in heating a mixture of sodium tungstate and sulphuric acid to produce tungstic oxides and sodium sulphate and applying heat interiorly of the tungstic oxides in the presence of a reducing agent.

In testimony whereof I have aflix'ed my signature.

\VARREN F. BLEECKER. 

